1. Field of the Invention
The present invention relates to a technical field concerning a light-emitting apparatus as, typified by a display device (apparatus) using a semiconductor device (typically, a transistor) as a device, especially, an electroluminescent display device, and a technical field concerning an electric appliance provided with the display device to an image display unit thereof.
2. Description of the Related Art
In recent years, a liquid crystal display device formed by integrating a transistor (especially, a thin film transistor) over a substrate and an electroluminescent display device has been well developed. These display device is operated as an image display device by forming a transistor on a glass substrate by using thin film formation technique, and disposing the transistor to each pixel arranged in a matrix configuration.
There are various specifications required to a region for displaying image of the display device (hereinafter, a pixel portion), for example, high-resolution with many number of dots, a large effective display region in each pixel, high luminance image display, no deterioration causing point defects or line defects throughout the pixel portion, or the like. In order to meet these specifications, it is required that not only transistors arranged in each pixel has good performance, but also technique for manufacturing transistors with good yields and in the stable process.
The way of preventing deteriorations of an organic compound become an important issue of an organic electroluminescent display device among other electroluminescent display device for obtaining reliability since the organic electroluminescent display device uses an organic compound as a light-emitting device serving as a light source. That is, in order to manufacture a high reliable display device, it is necessary that the reliability measure be implemented in view of not only the manufacturing process but also the deterioration with time of the completed light-emitting device.